Hi houseraccoon ,
About the 1. We've just found what's happening, and it's not really a bug.
Stock Central needs to do a multitude of calculations before showing all the info you can see in it. as the number of products increases more and more, the time spent by the server before displaying the info will grow exponentially. To prevent this, ATUM keeps the info in transients, and when a product is sold or saved, the transients are deleted to force ATUM to recalc.
The problem is when you change the settings, the transients aren't deleted, so the precalculated info doesn't change.
We've just included a fix for that, so when 'days to re-order' and 'Show sales in the last selected days' options change, the transients will be deleted.
This fix will be included in next ATUM's version.
Hope this helps,